I just went through this same thing with USPS weeks ago. Package delivered a day before I expected it by mistake to the neighbor, who denied all knowledge. USPS knew they put it on his doorstep, they had a GPS reading to prove it. Postal Inspector notified, they take missing packages, misdelivery, and package theft very seriously. A week later, after multiple contacts by USPS, my neighbor finally handed me my package.
The point is if USPS delivered a package with tracking, they know exactly when and where it was delivered, and anyone answering a phone at your local PO readily has access to that information. If the tracking says it was delivered, then it was delivered. But the PO does not yet know it was misdelivered until you make that clear to them, by telling them you never received it. The first thing, the very first thing they’re going to do is look and see where and when they delivered it. Then they’ll actually investigate, recover the package, and redeliver. But they’re not mind readers. As far as they know, everything is fine. It falls upon the person missing the expected package to make it clear to someone at the local PO that the package never arrived, even though the tracking indicates it was delivered. Why is this so difficult?